Researchers use brain scans to show how our brains seek rewards
It might help researchers understand addiction
Have you ever tried to stop yourself from doing something, but were unable to summon up the willpower? A new study finds your brain might be working against your best intentions, and scientists think they might know what could help you unlock your better self.
We’ve all seen it happen. Some well-intentioned co-worker stops at the bakery and brings the most delicious looking doughnuts to your meeting. Intellectually, you know doughnuts are among the foods you are not supposed to eat. They sit in front of you and they smell delicious. It’s like they’re calling out your name. By the end of the meeting, you have sliced off a piece of the German chocolate. OK, maybe two. Then, a slice of the cinnamon twist, and a slice of the red velvet. You may even have tried the salted caramel bacon, and you don’t even really like bacon.
What happened? Blame that Bad Idea Bear of a brain of yours, or more precisely, a chemical in it called dopamine. It’s the one your brain releases when you experience or anticipate pleasure or a reward, and it’s likely what talked you into having another bite (and another, and another).
To test this, scientists at Johns Hopkins University recruited 20 healthy people and put them in a brain scanner so they could observe what happened in their brain as they made choices. They asked the volunteers to identify objects on a computer screen. On the first day of the experiment, they were asked to pick out the red and green items. When the volunteer picked a green shape they got a quarter. When they found a red object, they earned $1.50. They did hundreds of these trials. The next day, they were put in the PET scanner again and as the scientists watched what happened in their brains, they asked participants to identify a particular shape, which came in a variety of colors. This time, there was no reward when they got the shape right and the color didn’t matter. But when a red or green object appeared on the screen, even if it wasn’t the object they were looking for, the volunteers were drawn to it. Dopamine flooded the part of their brains that controls attention.
Volunteers did find the shapes they were supposed to look for, but the color that had rewarded them distracted and slowed them down.
“The system that looks for potential rewards is responding even though you know you are not going to get a reward and you are supposed to be focusing on something else,” said author Susan Courtney, a professor in the department of psychological and brain sciences at Johns Hopkins. “One of the really interesting things is that different people responded to it differently. Some people were more distracted than others,” Courtney said. Those who were more distracted experienced a bigger dopamine release in the key part of the brain.
Shelly Flagel, the principal investigator at the Flagel Lab at the University of Michigan, studies dopamine in animal models. She said she thinks the study is particularly interesting because of those individual differences.
“Often, the reason we study this type of learning process is to help us better understand addiction, and the biggest problem with addiction is relapse,” Flagel said. “When you see this biological correlation between those who are and those who are not able to resist something, you can build on that.”
This applies whether your weakness is for doughnuts, Starbucks, or something more serious. When it comes to drugs or alcohol, people can relapse when they encounter certain places or paraphernalia they previously associated with their drug-taking behavior. Even if they have been clean for years and aren’t paying attention to these cues, their brains might be aware of them and trigger a craving.
Courtney said this study could lead to drug treatments that could help people with addictive behavior. There may also be behavioral approaches to help your brain release less dopamine.
“We know that habits are hard to suppress on their own,” Courtney said. “Often the most effective way to unlearn a habit is to replace it with a new one.”
For example, the next time you see a doughnut, you can consciously use it as a trigger to get up and get a glass of water instead. If you are conscious about enjoying that glass of water, maybe the next time you see a doughnut, you can trigger your brain to want something different.
“Telling people ‘don’t do that,’ especially if they have been previously rewarded, isn’t nearly as effective,” Courtney said.